Which version of Carbonite are you using, please? Are you using any other questing addons?

Also, and I'm guessing here, you are getting this error when you "alt" and right click the quest button in the quest watch window. That should open the Carbonite quest log (using the correct term will often alleviate confusion right from the start) with the correct quest already open.

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Ahhhh, the vagueries of the aging mind. Wait.... What was I saying?